Start with current, not watts
Current (A) = Power (W) ÷ Voltage (V)A 240W project is 10A at 24V, 20A at 12V, and 48A at 5V. That is why low-voltage high-power LED installations can require surprisingly substantial distribution conductors.
Approximate copper resistance by AWG
The calculator currently uses the following approximate resistance values for copper conductors:
| AWG | Approx. resistance (Ω / 1000 ft) |
|---|---|
| 18 | 6.385 |
| 16 | 4.016 |
| 14 | 2.525 |
| 12 | 1.588 |
| 10 | 0.999 |
Actual conductor construction, temperature, material, and product tolerances affect resistance. Use manufacturer data when precision matters.
Remember the return conductor
If the power supply is 30 ft from the tape, current travels approximately 30 ft out and 30 ft back. For a simple two-conductor feeder, use about 60 ft of conductor in the resistance calculation.
Circuit resistance = Ω/1000 ft × (2 × one-way feet) ÷ 1000 Voltage drop = Load current × Circuit resistanceVoltage drop and ampacity are separate checks
A conductor may be capable of carrying the current without overheating but still create too much voltage drop for a 5V or 12V LED load. Conversely, choosing a very large wire only for low voltage drop does not automatically make every connector, terminal, fuse, or tape lead suitable for the same current.
When to use multiple home runs
At higher currents, splitting one large load into several protected home runs can be cleaner than trying to carry the entire project current through one long feeder. This also makes power injection easier and can improve troubleshooting and serviceability.
Do not overlook the small parts
- Connector current ratings.
- Decoder/controller terminals.
- Factory pigtail wire size on the tape.
- Fuse or branch-protection sizing.
- Ambient temperature and bundling.
- Required cable listing and installation method.
Important: this guide is for planning low-voltage LED distribution, not for determining code compliance or mains-side branch-circuit conductor sizing. Follow applicable electrical requirements and listed equipment instructions.
Run the numbers for your project
Use the free calculator to estimate connected load, power-supply size, feeder voltage drop, power injection, controller channels, and addressable pixel groups.
Open LED Tape CalculatorRelated guides
Planning disclaimer
This guide is for project planning and education. Verify calculations against the exact tape, power supply, controller, conductor, connectors, and manufacturer instructions. Final installation must comply with applicable electrical requirements.